Industry news

How the filter works

2020-07-17

When the filter is working, the water to be filtered enters through the water inlet, flows through the filter screen, and enters the pipeline required by the user through the outlet for the process cycle. The particulate impurities in the water are trapped inside the filter screen. With such continuous circulation, more and more particles are trapped, and the filtration speed is getting slower and slower, while the sewage from the inlet still enters continuously, the filter holes will become smaller and smaller, thus creating pressure between the inlet and the outlet Poor, when the large difference reaches the set value, the differential pressure transmitter transmits the electrical signal to the controller, the control system starts the drive motor to drive the shaft to rotate through the transmission component, and at the same time the sewage outlet is opened and discharged from the sewage outlet, when the filter After cleaning, the pressure difference drops to the minimum value, the system returns to the initial filtration state, and the system operates normally. The filter is composed of shell, multi-element filter element, backwashing mechanism, and differential pressure controller. The transverse partition in the shell divides the inner cavity into upper and lower cavities. The upper cavity is equipped with multiple filter cores, which fully filters the space, significantly reduces the volume of the filter, and has a backwash installed in the lower cavity Sucker. During operation, the turbid liquid enters the lower cavity of the filter through the inlet, and enters the inner cavity of the filter core through the partition hole. Impurities larger than the gap of the filter core are trapped, and the clean liquid passes through the gap to reach the upper chamber, and is finally sent out from the outlet. The filter adopts high-strength wedge-shaped filter screen, and the filter element is automatically cleaned through pressure difference control and timing control. When impurities in the filter accumulate on the surface of the filter element, causing the pressure difference between the inlet and outlet to increase to the set value, or when the timer reaches the preset time, the electric control box sends a signal to drive the backwash mechanism. When the backwash suction cup port is directly opposite to the filter element inlet, the blowdown valve opens. At this time, the system releases the pressure and drains. A negative pressure zone appears inside the suction cup and the filter element, and the relative pressure is lower than the water pressure outside the filter element, forcing part of the clean circulating water from the outside of the filter element. Flowing into the inside of the filter element, the impurity particles adsorbed on the inner wall of the filter element flow into the pan and follow the water and are discharged from the sewage valve. The specially designed filter screen produces a spray effect inside the filter element, and any impurities will be washed away from the smooth inner wall. When the pressure difference between the inlet and outlet of the filter returns to normal or the time set by the timer ends, the material flows continuously and the backwash consumes less water during the entire process, realizing continuous and automated production. Filters are widely used in the fields of metallurgy, chemical industry, petroleum, papermaking, medicine, food, mining, electricity, and urban water supply. Such as industrial wastewater, circulating water filtration, emulsion regeneration, waste oil filtration treatment, continuous casting water system in the metallurgical industry, blast furnace water system, high-pressure water descaling system for hot rolling. It is an advanced, efficient and easy to operate automatic filtering device.

The water to be treated by the filter enters the body through the water inlet, and impurities in the water are deposited on the stainless steel filter screen, thereby generating a pressure difference. The pressure difference change of the inlet and outlet ports is monitored through the pressure difference switch. When the pressure difference reaches the set value, the electric controller feeds the hydraulic control valve to drive the motor signal. After the equipment is installed, the technicians will debug and set the filtering time and the cleaning conversion time. The water to be treated enters the body through the water inlet, the filter starts to work normally, and when the preset cleaning time is reached, the electric control valve of the water supply control valve 4. Drive the motor signal to trigger the following actions: the motor drives the brush to rotate, clean the filter element, and at the same time the control valve opens to drain the sewage. The entire cleaning process only needs to last for tens of seconds. When the cleaning is completed, the control valve is closed and the motor stops rotating. The system returns to its initial state and begins to enter the next filtration process. The inside of the filter housing is mainly composed of a coarse filter screen, a fine filter screen, a sewage suction pipe, a stainless steel brush or a stainless steel suction nozzle, a sealing ring, a corrosion-resistant coating, a rotating shaft, etc.

A simple filter is formed by dividing the container into upper and lower chambers with filter media. The suspension is added to the upper chamber, and enters the lower chamber through the filter medium under pressure to become a filtrate. The solid particles are trapped on the surface of the filter medium to form a filter residue (or filter cake). During the filtration process, the filter residue layer on the surface area of the filter medium gradually thickens, the resistance of the liquid through the filter residue layer increases, and the filtration speed decreases. When the filter chamber is full of filter residue or the filtration speed is too small, stop the filtration, remove the filter residue, and regenerate the filter medium to complete a filtration cycle.

The liquid must overcome the resistance through the filter residue layer and the filter medium, so there must be a pressure difference on both sides of the filter medium, which is the driving force for achieving filtration. Increasing the pressure difference can accelerate filtration, but the deformed particles after pressure are likely to block the pores of the filter medium when the pressure difference is large, but the filtration slows down.